The present invention relates to a method for producing a seasoning liquid, and more particularly to a method for producing a seasoning liquid which assumes a light color, undergoes a darkening process slowly, and has an excellent aroma with rich flavor and umami taste.
Production of an usukuchi soy sauce, which is a light-colored soy sauce, generally employs wheat serving as a source of starch, and soybeans or similar beans serving as a source of protein. However, conventional usukuchi soy sauces provides more saltiness than umami, because the amount of starch material to be mixed with protein material is slightly greater than that of the protein material, or salt concentration is raised so as to suppress coloration.
In addition, the darkening rate of conventional usukuchi soy sauces is very high, making the sauces unstable. Moreover, in order to attain a light color, fermentating period is shortened, or even further, a method for bleaching the produced soy sauce is employed. Thus, conventional usukuchi soy sauces have disadvantages in that the savory flavor is not satisfactory.
A method for producing a soy sauce having a light color and darkening slowly is disclosed in, for example, Japanese Patent Application Publication (kokoku) No. 57-48188, in which 10-30% (by weight) gluten is used together with at least one member selected from among corn, sorghum, or common millet serving as a source of starch, to thereby produce light-colored soy sauce having an excellent savory flavor and undergoing a darkening process slowly.
However, the aforementioned method has the following disadvantages: a) since starch materials other than wheat are employed, the aroma unique to wheat is not produced, b) corn, sorghum, and common millet have low glutamic acid content, and therefore the glutamic acid content of the resultant soy sauce also becomes low, resulting in an unsatisfactory umani taste, c) a satisfactory light color is not attained.
In view of the foregoing, the present inventors have undertaken various research efforts in an attempt to solve the above-described problems, and an object of the present invention is to provide a seasoning liquid which assumes a light color of No. 35 or higher in accordance with JAS color code (hereinafter, in the present description, the term xe2x80x9clight colorxe2x80x9d refers to a color of No. 35 in accordance with JAS color code or lighter colors), which darkens slowly, and which has an excellent aroma with rich flavor and umami taste, and have found that, when at least gluten is employed as an essential material for koji-making and fermentation, and the salt concentration of water employed for fermentation is controlled to 7-24%, satisfactory results can be attained, thus leading to completion of the present invention.
Accordingly, the present invention provides a method for producing a light-colored seasoning liquid, characterized by comprising koji-making by the employment of a raw material mixture containing soybeans or a similar material in an amount of 0-40% and, in an amount of 100-60%, raw material consisting of, on a dry weight basis, 25-100% gluten and 75-0% wheat, and mixing the thus-obtained koji product and 7-24% salt water for fermentation.
Gluten to be used in the present invention includes wheat gluten and corn gluten, with wheat gluten being particularly preferred. Either wet gluten or dry gluten obtained by drying wet gluten may be used, and dry gluten is particularly preferred. Examples of dry gluten include vital gluten powder and dry wheat gluten.
In the present invention, the wheat to be used as the starch material may be wheat grains or wheat flour.
The gluten or the mixture of gluten and wheat must be treated with heat so as to sufficiently denature the protein contained therein. Examples of preferred methods for heat treatment include a method in which steam is applied directly to gluten or a mixture of gluten and wheat, without addition of water, so as to control the water content thereof to fall within 12-18%, followed by formation of pellets by use of a pellet mill, and subsequently treating the resultant pellets in a high-pressure steam-cooking vessel at a gauge pressure of at least 1.0 kg/cm2 for two minutes or more, and a method in which gluten or a mixture of gluten is extruded at a temperature equal to or higher than 110xc2x0 C. by use of an extruder.
The thus-heat-treated gluten is completely deactivated, and exhibits no stickiness. Also, protein is denatured to a satisfactory degree. Therefore, when the thus-obtained gluten is appropriately ground, water is added thereto in such an amount that attains a water content of 35-50%, and used in koji-making, no operational problems arises. Rather, the swelling property of gluten provides an excellent bulkiness of material, which is quite beneficial to ventilated koji-making. In addition, when such gluten is mixed with heat-treated soybeans or a similar material, similar excellent koji-making property is exhibited. Moreover, the resultant koji product exhibits higher protease activity and glutaminase activity than in the case in which a greater amount of gluten is used.
In the present invention, soybeans or a similar material to be used as the protein material include, but are not limited to, defatted soybeans, whole soybeans, and ground soybeans. These are soaked in water, or water is added thereto; and then steam cooked, or alternatively, together with the aforementioned gluten and wheat flour, shaped through extrusion by use of an extruder at a temperature equal to or greater than 110xc2x0 C., to thereby sufficiently denature the proteins contained therein.
According to the present invention, very important factors for attaining the object of the present invention are to control the proportions of gluten and wheat such that, on the basis of dry weight, gluten accounts for 25-100% and wheat accounts for 75-0% with respect to the total amount of the two materials employed, and to control the proportion of soybeans or a similar material such that soybeans or a similar material accounts for 0-40% of the entirety of the raw materials employed.
Regarding the proportions of gluten and wheat, gluten may be used alone without wheat being employed. However, in the case in which wheat is employed, the proportion of wheat must account for 75% or less and gluten must be incorporated in an amount of at least 25%. In this connection, when gluten is incorporated in an amount smaller than the above-mentioned amount, although the resultant seasoning liquid has a light color, the seasoning is prone to lack umami, and thus the object of the present invention cannot be attained.
When soybeans or a similar material is incorporated, the amount thereof must be 40% or less. If the amount of soybeans or a similar material is in excess of 40%, the resultant seasoning has an intense umami taste; however, not only is reddish tint originating from soybeans or similar material intensified, but also the seasoning has a higher rate of darkening with unsatisfactory savory flavor, and thus the object of the present invention cannot be attained.
In the present invention, it is also necessary that a koji product obtained from koji-making by use of the aforementioned raw material mixture be charged with 7-24% salt water for maturing through fermentation. When the salt concentration is less than 7%, putrefaction occurs due to a growth of unwanted microorganisms, whereas when the salt concentration is more than 24%, umami taste of the resultant seasoning liquid is unsatisfactory, and thus the object of the present invention cannot be attained. The fermentation maturing is allowed to proceed, under routine monitoring and control of moromi mash, for 2-5 months at 10-30xc2x0 C., preferably for 2-3 months at 10xc2x0 C.; or alternatively, for one month at 10xc2x0 C. and subsequently for a further 1-2 months at 20xc2x0 C. Thereafter the resultant moromi mash is subjected to filtration or pressing, to thereby yield a seasoning liquid such as soy sauce. The thus-yielded soy sauce or any other type of seasoning liquid has a light color, a slow darkening rate, a very rich umami taste, and an excellent aroma. In the present invention, when the volume of the salt water to be charged is 1.35-1.65 times the weight of the raw material mixture, even more remarkable results can be obtained. In the case in which the volume is less than 1.35 times the weight of the resultant mixture, although a very rich umami taste can be attained, the color is darkened, which is not preferable.